Using Jackson and JSON Path to query and parse an arbitrary JSON node

Cassio Mazzochi Molin |

JSON Pointer is a string syntax for identifying a specific value within a JSON document, defined by the RFC 6901. Consider the following JSON:

{
  "firstName": "John",
  "lastName": "Doe",
  "address": {
    "street": "21 2nd Street",
    "city": "New York",
    "postalCode": "10021-3100",
    "coordinates": {
      "latitude": 40.7250387,
      "longitude": -73.9932568
    }
  }
}

The coordinates node can be identified by following JSON Pointer expression:

/address/coordinates

Jackson 2.3.0 introduced support to JSON Pointer and it can be handy when we want to query a specific node from a JSON document:

String json = "{\"firstName\":\"John\",\"lastName\":\"Doe\",\"address\":{\"street\":"
            + "\"21 2nd Street\",\"city\":\"New York\",\"postalCode\":\"10021-3100\","
            + "\"coordinates\":{\"latitude\":40.7250387,\"longitude\":-73.9932568}}}";

ObjectMapper mapper = new ObjectMapper();
JsonNode node = mapper.readTree(json);
JsonNode coordinatesNode = node.at("/address/coordinates");

Then the coordinates node could be parsed into a bean:

public class Coordinates {

    private Double latitude;
    private Double longitude;

    // Getters and setters omitted
}
Coordinates coordinates = mapper.treeToValue(coordinatesNode, Coordinates.class);